Charge dynamics of silicon nanocrystals in MOS capacitors

Abstract

In this paper we present a study of room temperature quasi-static capacitance–voltage and current–voltage characteristics of MOS capacitors containing silicon nanocrystals (Si-nc). We use the feedback charge method to measure simultaneously and independently the displacement current and the leakage current. As a result, an excess current attributed to the charging of the Si-nc with electrons and, simultaneously, a voltage shift of the capacitance are found. These excess current and voltage shift are found to strongly depend on the voltage scan rate and the initial state of charge in the Si-nc determined by a stress procedure applied before measurements. At each stage, the charge dynamics of the Si-nc is compared with that in reference samples and discussed. It is found that an average of 50% of Si-nc are charged by electrons.